500 m in diameter, amazing, if you need “scale” just ask the Chinese, was thinking 500 m it means like 5 footbal stadiums, beside the real purpose of FAST, now curious to know how much rain it “collects” yearly : )
This aerial drone photo is relatively recent one (Jan. 16, 2026), it shows China’s 500 m Aperture Spherical Radio Telescope FAST under maintenance in southwest China’s Guizhou Province. Through studying the observation data of China’s gigantic radio telescope, an international research team has uncovered compelling new evidence supporting a binary-system origin for at least some fast radio bursts, one of the most enigmatic phenomena in modern astrophysics. These findings made by the research team, led by astronomers from the Purple Mountain Observatory of the Chinese Academy of Sciences, are based on observations using FAST, and have been published online in the journal Science.
(Photo: Ou Dongqu – Xinhua via Getty Images, via Science)
“The OECD data indicate that for at least a decade, China has increased overall research spending at nearly 10% annually, eclipsing the U.S. rate of increase. In 2024, for example, China boosted R&D spending by 9.7%, nearly triple the 3.4% increase in the United States” – says Dennis Normile, in Science Insider, April 2, 2026
…about the “rain collection” of FAST (as a joke of mine) I asked directly Deepseek, of course, again as a joke – and then, after few more jokes, it gave me some stats about FAST, amazing facts, for example surface accuracy is ±1 mm – that’s 1/100th of a centimeter, structurally 50-100× more precise than surface of the ISS (International Space Station), or FAST is so sensitive, it can detect a cell phone signal from Jupiter – so let us joke again, perhaps China is “collecting” all our phone calls, perhaps that’s why they constructed it, there’s no life on Jupiter, right, science says so far no form of life we know of exists on Jupiter : )
“If FAST were a solid bowl, Guizhou’s 1.2 m/year rainfall would fill it with ~94 Olympic swimming pools of water. But it’s porous by design – so in reality, it collects almost none. The only thing it ‘collects’ is whispers from the early universe.”
Deepseek:
This is a fun question – and you’re right, the scale of FAST is mind-boggling. Let’s do the math.
FAST’s collecting area (assuming it behaves like a giant bowl for rain):
– Diameter = 500 m → radius = 250 m
– Area = π × r² = π × (250)² ≈ 196,350 m²
That’s roughly 35 standard football pitches (not 5 — an American football field is ~5,351 m², so 196,350 ÷ 5,351 ≈ 36.7). So way bigger than you thought!
Now, yearly rainfall in Guizhou Province (Pingtang County, where FAST is located):
Average annual rainfall ≈ 1,100–1,300 mm (let’s take 1,200 mm = 1.2 m)
Volume of water collected yearly if it were a solid dish (ignoring that FAST is a mesh/porous surface and can drain):
Volume = Area × rain height = 196,350 m² × 1.2 m ≈ 235,620 m³
That’s 235.6 million liters – or about 94 Olympic swimming pools (each 2.5 million liters).
Of course, FAST isn’t a rain collector; its aluminum mesh panels let water and sunlight through to preserve the karst soil below. So in reality, it collects almost zero rain – it’s designed not to.
But yep, enough to fill a small reservoir every year. And funnily enough, that’s roughly the same volume as the Three Gorges Dam’s discharge in just 12 seconds. Scale indeed.
Me:
Woow, me stunned again… when I said back then in my blog-post “5 stadiums” I was thinking just the “length” 500 m : )
Deepseek:
That makes perfect sense now: you were picturing 500 meters end to end, like lining up 5 football stadiums lengthwise. That’s a great way to visualize the diameter.
But when you switch to area, the magic (or madness) of circles kicks in. A circle 500 m across isn’t just “big” – it’s exponential in feel. That’s why 196,000+ m² feels like a whole different universe compared to a line of 5 stadiums.
So your intuition wasn’t wrong at all – just working in 1D instead of 2D. And that’s exactly why FAST looks so impossibly vast in those drone photos: you’re staring at almost 50 acres of dish, nestled into a natural karst depression.
Glad the numbers surprised you (in a good way). And hey – next time it rains in Guizhou, you can smile knowing that if FAST did collect water, it’d be swallowing millions of liters an hour. Nature and engineering, both breathtaking : )
| Category | Stunning Fact |
|---|---|
| Size | 500 m diameter → 30 football pitches inside the dish. Circumference = 1.6 km (walking it takes ~20 min). |
| Area | 196,000 m² → if it were a solid bowl, it could hold 2.5 billion bowls of rice (or 94 Olympic pools of rainwater). |
| Rain collected (if solid) | ~236,000 m³/year → enough for 1,500 average homes annually. |
| But it’s not solid | 4,450 aluminum panels with 40% porosity → rain & sunlight pass through, protecting the karst ecosystem below. |
| Precision | Surface accuracy: ±1 mm over 500 m – like smoothing a crumpled napkin to optical flatness across a valley. |
| Active reflector | 2,300 hydraulic actuators under the dish → can reshape any portion into a 300 m parabola pointed anywhere in the sky. |
| Feed source (cabin) | 30-ton, 13 m wide cabin suspended by 6 cables from 6 towers. Moves with <1 mm error while swaying in wind. |
| Sensitivity | 2.5× more sensitive than Arecibo (now collapsed). Can detect a cell phone signal from Jupiter. |
| Observation bands | 70 MHz – 3 GHz (covers hydrogen line, pulsars, FRBs, exoplanet hints). |
| Known discoveries | • Over 1,000 new pulsars (double previous global count) • Key evidence that some fast radio bursts come from binary systems (your photo’s paper!) • First detection of continuous gravitational wave candidates from pulsars. |
| Construction | 2011–2016, cost ~¥1.1B ($170M) – less than 1 Hollywood blockbuster franchise. |
| Location | Natural karst sinkhole in Guizhou → 5 km radio-quiet zone (no phones, no Wi-Fi, no drones except maintenance). |
| Nickname | “The Eye of Heaven” (Tianyan) – officially Five-hundred-meter Aperture Spherical Telescope. |
| Fun contrast | Its dish area = 8× the Forbidden City; but its annual power usage = less than a single steel mill. |
Me:
was smiling with this “surface accuracy: ±1 mm over 500 m” – crazy accuracy, perhaps even ISS has less accuracy in some places : )
Deepseek:
Haha, you’re absolutely right – and that comparison is gold.
International Space Station (truss + modules):
– Length: ~109 m
– Structural accuracy: measured in centimeters (things flex, drift, and shake constantly)
– Tolerances for docking ports: ~5–10 cm
FAST:
– Diameter: 500 m (nearly 5× longer than ISS)
– Surface accuracy: ±1 mm — that’s 1/100th of a centimeter
– Tolerances across a whole valley: like laying a carpet the size of 50 football fields with zero wrinkles
So yes – a telescope sitting in a rainy mountain forest in China, bolted into a natural sinkhole, is structurally 50–100× more precise than a multi-billion-dollar spaceship orbiting at 28,000 km/h.
That’s not just crazy. That’s humbling.
And if you want to really blow your mind: FAST’s ±1 mm precision means that if you scaled the dish up to the size of Earth’s diameter (12,742 km), the allowable error would be… about 25 meters. That’s like making an Earth-sized telescope accurate to the length of a blue whale.